Micrometer gauge



Nov. 6, 1951 C. E. LINN ETAL MICROMETER GAUGE Filed Feb. 15, 1950 FIGZ.

Charles E.Linn & Paul H. Hummel.

INVENTORS.

ATTORNEY Patented Nov. 6, 1951 Charles E. Linnand Paul H Hummel, Lansing, Mich, assignors, to. Automotive Service Tools, 1110., Lansing, Mich., a corporation of Michigan ApplicationFebruar-y 15, 1950, Serial No. 144,298 1 Claim. (01. 33-164) This invention relates to micrometer gauges.

and particularly to special purpose gauges formeasuring the clearance between the valve stem cap and the cap end of so called release type rotating poppet valves of internal combustion engines.

There is in general use a type of poppet valve called a release type rotating poppet valve. It is so named because when the valve is opened by the valve cam and tappet or Valve earn, the pressure of the valve spring on the valve is released just prior to the opening of the valve, thereby relieving friction and permitting the Valve to rotate slightly under any rotational force applied to it. Thus the valve is not apt to wearunevenly, thereby lengthening its life.

The present invention is a simple gauge for accurately measuring the clearance between the Valve stem cap and cap end of such a valve so that adjustment may be made in the clearance between those two parts.

In the drawings accompanying thisspecification:

Figure 1 is a fragmentary cross-sectional view of an internal combustion engine having a poppet.

valve of the release type;

Figure 2 is a fragmentary cross-sectional View of a portion of the valve. on an enlargedscale,

showing the clearance between the valve cap" and cap end of the valve;

Figure 3 is a similar cross-sectional view of the parts shown in Figure 2 with the clearance taken up; and

Figure 4 is a fragmentary cross-sectional'view showing the present invention in use.

Figure 1 illustrates a portion of the engine block of an internal combustion engine it]. It is equipped with the usual cylinders and. pistons H, only one or" which is shown. An exhaust valve of the release type rotating poppet I2 is mounted in a valve guide in the engine block. The stem of the valve is of uniform diameter-for most of its length, but adjacent the stem end it is relieved at it to form a fiat shoulder l4. See Figures 2 and 3. An annular valve spring retainer l5 surrounds the valve stem. It has a central opening somewhat larger than the greatest diameter of the stem. The spring retainer is provided with a central recess l6 around the opening which receives two semi-circular keys I which when placed together form a split ring IT. The opening through the keys when they are placed together is only slightly larger than the relieved portion [3 of the valve stem and small er than the shoulder [4. The keys lock the j 2 spring retainer on the valve and transmit the pressure of a valve spring 26 to the valve.

A hollow cap [8 fits loosely on the stem end of the valve. cap I8 is slightly greater than the thickness of the shouldered end of the valve stem, thereby providing release clearance l9 between the cap,

13 and the cap end of the valve stem. See Figure 2. This clearance should be between .002" and .006.

The valve is lifted by means of a cam shaft.

26 through the medium of a push rod 2| and rocker arm 22 pivotally mounted on the engine block at 23. The push rod 2| is connected to the rocker arm by a short threaded stud 2A having adjusting nuts 25 thereon to permit the adjustment of tappet clearance between the rocker arm 22 and the cap it. customary clearance to accommodate expansion of the valve and push rod and other parts as the engine becomes hot.

Due to the projection of the side walls of the cap [8 beyond the shoulder l4, when pressure is applied to the cap through the rocker arm 22 the cap [8 acts against the keys I! and depresses the spring retainer I5 and spring 26 slightly be! fore the cap it bottoms on the cap end of the, stem ofthe valve 12. That takes up the clearance l9 and relieves the pressure of the spring against the shoulder M of the valve.- See Figure 3. The only forces then preventing rotation of the valve are those due to friction between the valve guide and valve stem and between the cap 18. and the cap end of the valve stem. The valve may then slowly creep in a rotary motion due to the flow of exhaust gases around the valve head, as well as a slight rotating force imparted to the valve by the valve spring. This rotating motion tends to keep the valve head and valve seat clean and minimizes uneven burning from the flow of hot exhaust gases.

After the clearance l9 has been taken up, further movement of the rocker arm opens the valve in the usual manner.

In time the keys ll will wear at their area of contact between them and the shoulder M of the valve stem. That wear may become so great that the clearance I9 may exceed the preferred maximum of .006", causing greater movement between the valve cap and stem end of the valve when the valve is lifted.

It is desirable to check the clearance l9 periodically, and if it becomes excessive correct the same. That correction may be done in most instances by grinding off the edges of the side The depth of the interior of the.

This clearance is thev wall of the cap [8 where they contact the keys l1. Of course, in correcting the clearance it is necessary to be sure that the walls of the cap l8 are not ground excessively so that the clearance becomes less than .002". The present invention is for the purpose of determining whether or not adjustment is necessary, as well as for determining when the proper adjustment has been made.

The present invention is a special micrometer gauge which consists of an inner sleeve 30, an outer sleeve 3|, a central pin 32 and a set screw 33. The inner sleeve 30 has a cylindrical bore therethrough just large enough to be a loose sliding fit over the cap end of the valve [2. A portion of the exterior of the inner sleeve is threaded as at 34. An index mark 35 is scored on the outside of the sleeve. See Figure 4.

The set screw 33 is threaded through the wall of the inner sleeve 30. It is used for securing the inner sleeve to the pin 32, as will more fully appear presently.

The outer sleeve 3| is interiorly threaded intermediate its ends to cooperate with the threads 34. The interior of the outer end of the outer sleeve is provided with a bore of the same diameter as the bore within the inner sleeve 30. The end of the outer sleeve adjacent the valve stem is graduated as at 36 so that rotation of the outer sleeve relative to the inner sleeve will indicate contraction or elongation of the overall length of the two sleeves when rotated relative to the index mark 35. Preferably the graduations are such as to indicate relative axial movement of the two sleeves in thousandths of an inch.

The pin 32 is cylindrical and is a loose sliding fit within the bore in the sleeve 30 and the upper end of the sleeve 31. Preferably it is provided with an amiular recess which receives a split ring 31 to prevent the pin from accidentally falling out of the two sleeves. The pin is accurately ground to a length equal to the overall length of the two sleeves when the index marks are set to indicate a zero reading.

To use the gauge the engine is dismantled sufliciently to gain access to the stem end of the valve l2. The cap I8 is remoted from the valve stem and the inner sleeve slipped over the end of the valve stem and rested against the keys IT, as indicated in Figure 4. The set screw 33 is loosened to permit the pin 32 to engage the adjoining end of the valve stem. The set screw is then tightened to hold the pin firmly in place. As will be evident when that is done, the end of the pin opposite the valve stem projects out of the gauge. The cap I8 is then placed over the projecting end of the pin 32 and held against the adjoining end of the outer sleeve 3|. The outer sleeve 3| is rotated sufliciently so that the cap will just contact the end of the pin. With the gauge contacting the keys [1, the pin 32 against the valve stem, the cap l8 against the other end of the pin, and the outer sleeve touching the cap IS, the gauge will indicate whether or not there is any clearance, and will register the amount of that clearance. If the clearance is less than .002 or more than .006" suitable adjustment should be made as previously described. The gauge can then be removed from the valve stem and the cap replaced thereon.

In the case of overhead valves such as shown, the present invention can be utilized in the determination and correction of the clearance between the cap [8 and valve stem without removing the valve. It can also be used in the determination of the clearance in the case of any other release type rotating poppet valve. In most of those cases, however, it is necessary to completely remove the valve from the engine in order to determine the clearance and correct the same if necessary.

From the foregoing it will be seen that the present invention provides an extremely simple and accurate gauge for determining the cap clearance between the cap and valve stem of valves of the release type. It is particularly useful in the case of overhead valves because it is unnecessary to remove the valve from the engine.

The scope of the invention is indicated in the appended claim.

We claim:

A micrometer gauge comprising inner and outer coaxial sleeves having portions thereof in overlapping relationship, one end of each sleeve projecting axially beyond the corresponding end of the other sleeve, said sleeves having cooperating internal and external threads respectively on overlapping portions thereof and being open at both ends, cooperating indicia on external portions of said sleeves to indicate the overall expansion and contraction of the gauge, and a cylindrical pin received in said sleeves for axial movement, said pin being equal to the overall length of said sleeves when the latter are adjusted to predetermined relative setting, said pin normally projecting axially outwardly beyond the outer sleeve thereby providing a recess within the inner sleeve between the outer end of the latter and the corresponding end of the pin, and means for fixedly attaching said pin to one of said sleeves.

CHARLES E. LINN. PAUL H. HUMMEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 953,933 Tucker Apr. 5, 1910 2,085,380 Muller June 29, 1937 2,193,939 Sanford Mar. 19, 1940 2,445,060 Gearhart July 13, 1948 2,498,969 Vobeda Feb. 28, 1950 

